# Lesson 5: Adding Binary Numbers

## Digital Information

## Adding Binary Numbers

You know what 1 + 1 is, right? Well, what's 1_{2} + 1_{2}? (The small 2 at the end of each 1 lets you know it's a binary number.) The answer? It's 10_{2} (the binary number for 2).

Adding binary numbers is pretty easy. The key is carrying the 1, just like you do in decimal (base 10) system addition. Know how you carry a 1 over to the next place column every time two decimal numbers in a place column add up to 10 or more? Adding two binary numbers is just like that too. You carry a 1 over to the next place column every time you add 1_{2} + 1_{2} in a place column—leaving a 0 in that place column. Add three 1_{2} numbers in the same place column and you carry a 1 and leave a 1 in the column.